I'm not a distributed systems person, but I guess this is a _much_ simpler version of something like https://en.wikipedia.org/wiki/Chandy%E2%80%93Lamport_algorithm. E.g. this part is similar to what I was describing as recording internal inputs during the checkpointing interval: "If a process receives a marker after having recorded its local state, it records the state of the incoming channel from which the marker came as carrying all the messages received since it first recorded its local state."

Anyway, I think I have another solution. Let's take the article's two-component example of a CPU and a APU. For deterministic replay, normally you only need to record external inputs, not internal inputs (i.e. cross-component interactions). But you can use per-component "ragged checkpoints" to resolve the alignment problem. During the checkpointing interval you're also recording internal inputs, so you can step forward the lagging component in isolation to catch up when restoring a checkpoint.

I normally never read HN but a specific thread was linked in the Hegel thread on Lobsters, so I guess I brought it upon myself for clicking through that link.